Electrode binder for a nonaqueous secondary battery and nonaqueous secondary battery electrode

Abstract

An electrode binder for a nonaqueous secondary battery; and a nonaqueous secondary battery electrode. The electrode binder for a nonaqueous secondary battery contains a resin component and is water-soluble. The surface free energy γB at 23° C. is 70 mJ/m2 or less, and the dipole component γPB of the surface free energy is 26 mJ/m2 or less.

The invention claimed is: 
     
       1. An electrode binder for a nonaqueous secondary battery, which is water-soluble and comprises a resin component and a surfactant,
 wherein a surface free energy YB at 23° C. is 70 mJ/m 2  or less; 
 a dipole component γ P   B  of the surface free energy is 26 mJ/m 2  or less; 
 the surfactant is polyoxyethylene alkyl ether; 
 the resin component comprises
 a polymer of a compound having an ethylenically unsaturated bond, and 
 a dispersant selected from the group consisting of carboxymethyl cellulose and its metal salts; 
 
 the polymer is a copolymer of compounds comprising
 a compound having an ethylenically unsaturated bond selected from the group consisting of (meth)acrylic acid and (meth)acrylic acid salt, and 
 another vinyl compound selected from the group consisting of styrene, a divinylbenzene, a butadiene, an N-vinylacetamide, an N-vinylformamide, a vinyl alcohol, a vinyl acetate. 
 
 
     
     
       2. The electrode binder for a nonaqueous secondary battery according to  claim 1 , wherein the surface free energy γ B  is 66 mJ/m 2  or less. 
     
     
       3. The electrode binder for a nonaqueous secondary battery according to  claim 1 , wherein the dipole component γ P   B  of the surface free energy is 22 mJ/m 2  or less. 
     
     
       4. The electrode binder for a nonaqueous secondary battery according to  claim 1 , wherein a hydrogen bonding component γ h   B  of the surface free energy is 24 mJ/m 2  or less. 
     
     
       5. A nonaqueous secondary battery electrode, comprising a current collector and an electrode active material layer,
 wherein the electrode active material layer comprises an electrode binder for a nonaqueous secondary battery according to  claim 1 , and an electrode active material; and 
 the electrode active material layer is formed on the current collector. 
 
     
     
       6. The nonaqueous secondary battery electrode according to  claim 5 ,
 wherein the electrode active material layer comprises 85% by mass or more and 99% by mass or less of the electrode active material. 
 
     
     
       7. The nonaqueous secondary battery electrode according to  claim 5 , wherein the electrode active material comprises a Si element-containing material and a carbon material. 
     
     
       8. The nonaqueous secondary battery electrode according to  claim 5 , wherein a peeling strength of the electrode active material layer with respect to the current collector is 30 mN/mm or more. 
     
     
       9. A nonaqueous secondary battery, which comprises the nonaqueous secondary battery electrode according to  claim 5 ,
 wherein the nonaqueous secondary battery uses an alkali metal ion as a charge carrier. 
 
     
     
       10. The nonaqueous secondary battery according to  claim 9 , comprising
 an organic solvent solution of an alkali metal salt, as an electrolyte solution. 
 
     
     
       11. The nonaqueous secondary battery according to  claim 10 , wherein the organic solvent of the electrolyte solution comprises at least one kind selected from the group consisting of a carbonate compound, a nitrile compound and a carboxylic acid ester.